Added appropriate delete statements.

src/dawn/asset/AssetManager.hpp

@@ -37,6 +37,12 @@ namespace Dawn {
         return asset;
       }
 
+      template<class T>
+      void unload(std::string name) {
+        assertUnreachable();
+        //should delete the asset for you
+      }
+
       ~AssetManager();
   };
 }